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The attitude and orbit control subsystem (AOCS) provides attitude information communications service equipment, and scientific instruments. Control is. An operating communications satellite system consists of Physical Structure. Attitude and Orbit Control System. (AOCS). Power System. Thermal Control. oriented framework for Attitude and Orbit Control System or AOCS of satellites. Understanding the case study requires some familiarity with the AOCS domain.

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The letter use is housekeeping, since these subsystems serve to support the communications system. The TTCM subsystem present at earth station monitors the position of satellite. These three axes define the altitude of satellite. Xatellite that this is not a bright source avoidance cone, but driven by requirements on the spacecraft’s alignment with respect to the Sun to ensure sufficient energy supply and thermal stability.

It is also used to control the antenna pointing and communication system configuration to suit current sahellite requirements and to operate switch on the satellite. Due to this, the spin axis gets stabilized and the satellite will point in the same direction. The design of the AOCS has been driven by a fail-safe approach. The maximum rotation speed of the reaction wheels is rpm. The tracking system is located at this earth station and provides information on the range and the elevation and azimuth angles of the satellite.

However, should any serious anomaly occur, such as a prolonged loss of contact, XMM-Newton will automatically enter a survival mode and wait for direct control to be re-established from Earth.

Satellite Communication AOC Subsystem

In this way, the AOC subsystem takes care of the satellite position in the right orbit and at right altitude during entire life span of the satellite in space. All eventual failures must be detected.

This subsystem consists of rocket motors that are used to move the satellite back to the correct orbit when external forces cause it to comjunication off station and gas jets or inertial devices that control the attitude of the satellite. The direction of this motor will be opposite to the rotation of satellite body, so that the antennas point towards earth. Zatellite drum is covered with solar cells. It is responsible for the detection of anomalies of whatever origin and their correction.


In this method, the body of the satellite rotates around its spin axis. We know that satellite may deviates from its orbit due to the gravitational forces from sun, moon and other planets.

This site was designed with the. Power systems and rockets are present in this drum.

Satellite Communication – AOC Subsystem

The pointing accuracy of the 10 m long XMM-Newton is 0. During launching phase, the satellite spins when the small radial gas jets are operated. In addition, a solar aspect angle within the range must be maintained at all times. On the basis of data supplied by a star-tracker telescope, which recognises the different star formations in its field of view, the AOCS computers calculate the appropriate momentum of the reaction wheels for precision manoeuvring of the spacecraft during observations or to change the target.

Given XMM-Newton’s very specific orbit highly elliptical, irregular eclipse seasons, Sun avoidancethis required very complex hardwired logic within the unit.

These forces change cyclically over a hour period, since the satellite moves around the earth. ESA’s X-ray space observatory targets distant X-ray sources for long periods often exceeding ten hours and one of the key requirements of the satellite is its very high pointing accuracy and stability.

Before delivery for integration into the spacecraft, the AOCS system underwent several weeks of intensive testing, and subsequent System Validation Tests on the assembled satellite have confirmed its perfect operation. Create your website today. It is usually composed of one or more antennas, which receive and transmit over wide bandwidths at microwave frequencies, and a set of receivers and transmitters that amplify and retransmit the incoming signals.

This set of three axis provides the information about orientation of the satellite with respect to reference axes.

Then, it will resolve that issue by bringing the satellite into the correct orbit. Let X, Y and Z are another set of Cartesian axes. The fully redundant AOCS represents some kg of electronics: They will provide the rotation in both directions of the three axes.


The satellites, which perform this kind of operation are called as de-spin. The AOCS has also been designed to enable the satellite to operate in an autonomous mode for 36 hours, and during eclipses.

Based on telemetry data received from the satellite and orbital data obtained from the tracking system, the control system is used to correct the position and attitude of the satellite. If there is a change in altitude of the satellite, then the angles between the respective axes will be changed. An electric motor drives this communication system. You can also try this books 1. Orbit control subsystem is useful in order to bring the satellite into its correct orbit, whenever the satellite gets deviated from its orbit.

Reaction wheel courtesy of MMS. Most satellite antennas are designed to operate in a single frequency band, for example, C band or Ku band. A satellite which uses multiple frequency bands usually has four or more antennas. Learn all you need in order to create a. These systems are partly on the satellite and partly at the controlling earth station.

From then on, the X-ray observatory’s life in space, for more than ten years, has been beating to the rhythm of its “electronic heart”. By continuing to use the site you are agreeing to our use of cookies.

The telemetry system sends data derived from many sensors on the satellite, which monitor the satellites health, via telemetry link to the controlling earth station. Satellites are of this type are called as spinners.

Communication subsystem communicayion placed on top of the drum. Following are the two methods to make the satellite that is present in an orbit as stable. If there is any change in satellite orbit, then it sends satllite signal regarding the correction to Orbit control subsystem.

Missions Show All Missions. Likewise it will never point to within The receiver-transmitter units are known as transponders.